This invention relates to telecommunications systems and their installation, and more particularly, to a flared cable support used for installing cables capable of high speed data rate transmissions used in such systems.
Telecommunication systems used in commercial or residential buildings typically involve a number of user sites between which various types of information is transferred. Cables are used to interconnect the user sites. A computer or other piece of telecommunications equipment is connected to an outlet which is a wall mounted outlet adjacent a work area. Cables are strung inside the walls and above the ceilings of the building to interconnect or cross-connect the outlets to each other. Thus, a routing from one outlet to another includes vertical cable sections extending inside a wall, and horizontal cable sections extending above the ceiling of the room or rooms in which the communications equipment is located. Telecommunications systems include a central control unit located in closet or room, and all of the system cabling is routed to and from this central unit.
Horizontal cabling is that portion of the cabling system extending from the work area outlets or connectors to a horizontal cross-connect located in closet or room where the central control unit is placed. The cabling systems employed operate over various transmission media. Three types of cables are currently recognized for use in cabling systems. These include
100 ohm 24 gauge unshielded twisted pair cable (UTP) PA1 150 ohm 24 gauge shielded twisted pair cable (STP) PA1 fiber optic multimode 62.5/125 micron cable. PA1 the provision of such a cable support to facilitate routing cables through a structure and, in particular, around bends in the structure; PA1 the provision of such a cable support to have flared ends the radius of each of which corresponds to the bend radius for a cable specified in the ANSI/TIA/EIA-568-A Building Telecommunications Wiring Standards; PA1 the provision of such a cable support to be equally useful with whatever type and category of approved cable is used in a telecommunications system; PA1 the provision of such a cable support to be readily installed in place using bridle rings or the like which mount the cable support in a desired location, or to be retrofitted into previous installations where existing cable supports are not adequate to prevent droop or allow an adequate bend radius at turns; PA1 the provision of such a cable support which is installed with existing supports and allows a cable to be quickly and easily fitted into the new support; PA1 the provision of such a cable support to be of a two-piece construction in which the pieces are identically formed, readily connected together on site and can be used interchangeably regardless of the location used, that is, for a vertical run of cable, a horizontal run, or a corner; PA1 the provision of such a cable support in which a cable installer can carry pieces forming the support with him either assembled or disassembled, and if disassembled, can assemble a support by hand and with no special tools required; PA1 the provision of such a cable support to be of a made of a material compatible with National Electrical Code requirements for the environment in which the support is installed; PA1 the provision of such a cable support which is small enough that the supports required for a cable installation are easily stored where needed for quick access by the cable installer; and, PA1 the provision of such a cable support which is of a two-part construction using identically formed components which are readily assembled on site for the support to be low cost and available in a variety of sizes for use in all types of cable installations.
It is well-recognized that data can be transferred to, from, and within a telecommunications system at different transfer rates. With respect to UTP cable, for example, there are different categories of cable for different transmission rates. Category 3 is for transmission rates on the order of 16 mhz, Category 4 is for transmission rates on the order of 20 MHz, and Category 5 is for rates of 100 mhz. For higher rate data communications (100 MHz or higher) it is very important that the telecommunications media be properly installed in the building. Cable installation practices in this regard are set forth in the ANSI/TIA/EIA-568-A Building Telecommunications Wiring Standards.
One element addressed in these standards relate to the bend radius of a cable when, for example, its routing changes from vertical to horizontal or vice versa. In this regard, paragraph 10.6.3.2 of the standard reads as follows:
"in spaces with UTP terminations, cable bend radii shall not be less than four-times the cable diameter for horizontal cable."
The UTP cable referred to in the standard consists of 24 AWG thermoplastic, insulated, solid conductors formed into four individually twisted pairs and enclosed in a thermoplastic jacket. The diameter of such a cable is 0.25" (6.35 mm). It has been found, that if these bend radii are not met, the cable will have a kink or crimp in it. This adversely effects transmission so that the desired data transmission rate cannot be achieved. This, in turn, seriously comprises operation of the system. It is important therefore to provide a horizontal cable installation in which specified bend radii are easily met during cable installation, as well as subsequently thereto when work on or around cables may take place.
In addition to the need to insure proper installation of cables during new system construction, it would also be advantageous if retrofitting of cables in previous constructions could also be accomplished. It has been known for some time to use a wall mounted clip or hanger from which the cable is supported. For horizontal runs of cable, and for corner turns, it is particularly important that the cable not droop and that the bend radius of the cable exceed the minimum bend radius previously referred to. Otherwise, too much droop or too tight a bend effects the optical characteristics of a fiber optic cable, degrading data transmission quality, and introducing cross-talk, among other problems. Some hangers now used for new installations provide a flared support by which cable turns cannot be less than the desired minimum radius so to alleviate the problems outlined above. One hanger of this type is referred to as a J-shape hanger. Such hangers have a curved surface at a lower, curved end of the J, this curved portion of the hanger flaring outwardly to the sides of the hanger. Once a cable is fitted in the hanger, a separate tie is used to close the top of the J and secure the cable in place. However, for retrofitting of prior installations, such hangers cannot be used because their design is such that in order for them to be used, the cable must be removed from its prior fitting and the new hanger substituted. This is a time consuming and expensive operation.